METROLOGY METHOD, APPARATUS AND COMPUTER PROGRAM
First Claim
1. A metrology method comprising:
- obtaining measurement data relating to a measurement of a target formed in at least two layers on a substrate by a lithographic process, the measurement data being derived from a corresponding pair of non-zeroth diffraction orders;
obtaining simulation data relating to simulation of a measurement of the target as defined in terms of geometric parameters of the target, the geometric parameters comprising a variable geometric parameter; and
minimizing a difference between the measurement data and simulation data, so as to directly reconstruct a value for the variable geometric parameter.
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Abstract
A metrology method, and associated metrology apparatus, that includes measuring a target formed in at least two layers on a substrate by a lithographic process and capturing at least one corresponding pair of non-zeroth diffraction orders, for example in an image field, to obtain measurement data. A simulation of a measurement of the target as defined in terms of geometric parameters of the target, the geometric parameters including one or more variable geometric parameters is performed and a difference between the measurement data and simulation data is minimized, so as to directly reconstruct values for the one or more variable geometric parameters.
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Citations
20 Claims
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1. A metrology method comprising:
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obtaining measurement data relating to a measurement of a target formed in at least two layers on a substrate by a lithographic process, the measurement data being derived from a corresponding pair of non-zeroth diffraction orders; obtaining simulation data relating to simulation of a measurement of the target as defined in terms of geometric parameters of the target, the geometric parameters comprising a variable geometric parameter; and minimizing a difference between the measurement data and simulation data, so as to directly reconstruct a value for the variable geometric parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A metrology apparatus comprising a processor configured to at least:
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obtain measurement data relating to a measurement of a target formed in at least two layers on a substrate by a lithographic process, the measurement data being derived from a corresponding pair of non-zeroth diffraction orders; obtain simulation data relating to simulation of a measurement of the target as defined in terms of geometric parameters of the target, the geometric parameters comprising a variable geometric parameter; and minimize a difference between the measurement data and simulation data, so as to directly reconstruct a value for the variable geometric parameter.
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20. A non-transitory computer-readable medium comprising program instructions operable to cause a computer system to:
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obtain measurement data relating to a measurement of a target formed in at least two layers on a substrate by a lithographic process, the measurement data being derived from a corresponding pair of non-zeroth diffraction orders; obtain simulation data relating to simulation of a measurement of the target as defined in terms of geometric parameters of the target, the geometric parameters comprising a variable geometric parameter; and minimize a difference between the measurement data and simulation data, so as to directly reconstruct a value for the variable geometric parameter.
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Specification